1. Field of the Invention
The present invention relates to an enclosure structure of electronic equipment such as a rack-mount disk array apparatus.
2. Description of the Related Art
Reference is made to FIG. 1 to describe a conventional rack-mount disk array apparatus. In a disk array apparatus 2, there is provided a back panel 6 at the middle portion of an enclosure 4 mounted to the rack, with a plurality of hard disk units 8 provided on the front surface portion of the back panel 6 and a plurality of interface (I/F) units 10 and power supply units 12 provided on the rear surface portion of the back panel 6. The hard disk units 8 are mounted from the front surface side of the enclosure 4 for replacement thereof.
Japanese Patent Application Laid-Open Publication Nos. 2003-36669, 2002-343075, 08-137631 and 06-215553 are available as patent documents related to such an enclosure structure of electronic equipment such as such disk array apparatus.
In Japanese Patent Application Laid-Open Publication No. 2003-36669, there are disclosed electronic equipment and a rack housing the electronic equipment in which, for easy replacement of hard disk devices in a rack-housed server unit, the server unit is configured with outer and inner cases, with a movable portion capable of moving downward attached to the inner case and hard disk devices housed in two rows, and in which, in the case of replacement of hard disk devices located toward the back, the inner case is drawn out, and further the movable portion is lowered so as to expose the end surfaces of the hard disk devices located toward the back. In such a configuration, all hard disk devices can be replaced from the front surface side, with no need to detach the server unit from the rack at the time of replacement.
In Japanese Patent Application Laid-Open Publication No. 2002-343075, there is disclosed a disk array that allows easy performance of tasks such as replacement and addition of hard disk units and prevents occurrence of shorting failure as a result of contact between signal cable and slim enclosure. In this disk array, a plurality of slim enclosures, each equipped with a hard disk unit, are housed in a rack so as to be slidable, with the slim enclosures provided with a tray having a front opening for allowing entry of the hard disk unit so as to be freely attachable/detachable and a connector for connecting the hard disk unit that has entered from the front opening. The tray is supported so as to be movable to the disk attachment/detachment position that brings the front opening away from the bottom plate of the slim enclosure and to the use position that brings the front opening close to the bottom plate.
In Japanese Patent Application Laid-Open Publication No. 08-137631, there is disclosed a disk array apparatus in which 2.5-inch or smaller hard disks can be installed using the form factor of 5.25-inch or 3.5-inch hard disk of a conventional disk array apparatus. As its configuration, four 2.5-inch hard disks are arranged three-dimensionally in a slot corresponding with the form factor of 5.25-inch hard disk of disk array apparatus. In the event of a failure of a hard disk, one pulls out the slot by grabbing the handle at the front of the slot, pulls out the faulty hard disk by grabbing the handle located toward the front, replaces the faulty hard disk with a new one, inserts the new hard disk into the slot by reversing the procedure for withdrawal and puts the slot back into the disk array apparatus to complete hot-swap.
In Japanese Patent Application Laid-Open Publication No. 06-215553, there is disclosed an easy-to-install-and-detach disk drive carrier assembly that is equipped with a 3.5-inch disk head assembly (HDA) and an electronic card pack in a detachable manner.
Incidentally, description will be given of hard disk units mounted in such a disk array apparatus with reference to FIGS. 2A and 2B. FIG. 2A shows a case in which 3.5-inch hard disk (HDD) units are mounted in a rack, whereas FIG. 2B shows a case in which 2.5-inch hard disk-units are mounted in the same rack. In these disk array apparatuses 2, size reduction of hard disk units 8, mounted in the enclosure 4, for example, from 3.5-inch type to 2.5-inch type, will result in a reduced storage capacity per unit height of the rack if the same unit arrangement is used as in the conventional apparatus.
In a disk array apparatus 2A shown in FIG. 2A, the size of the 3.5-inch hard disk units 8 mounted in a rack 14 is 3U, thus making the height 36U due to a 12-stage configuration. Here, 1U=44.45 mm (1.75 inches) based on EIA standard. Letting the number of the hard disk units 8 installed in the direction of width of the rack 14 be 15, the storage capacity of each of the hard disk units 8 be, for example, 300 GB, and the storage capacity per the rack 14 in this case be M1, then the storage capacity M1 is:M1=12×15×300 [GB]=54,000 [GB]
In this case, the storage capacity per 1U or M1/36U is:M1/36U=54,000 [GB]/36U=1,500 [GB]
In contrast, in a disk array apparatus 2B shown in FIG. 2B, the size of 2.5-inch hard disk units 18 mounted in a rack 16 is 2U, thus making the height 36U similarly due to an 18-stage configuration. Letting the number of the hard disk units 18 installed in the direction of width of the rack 16 be 24, the storage capacity of each of the hard disk units 18 be, for example, 73 GB, and the storage capacity per the rack 16 in this case be M2, then the storage capacity M2 is:M2=18×24×73 [GB]=31,536 [GB]In this case, the storage capacity per 1U or M2/36U is:M2/36U=31,536 [GB]/36U=876 [GB]
Thus, if the 3.5-inch hard disk units 8 are changed to the 2.5-inch hard disk units 18, the storage capacity per the rack 16 is low, despite increased number of the hard disk units 18, because the storage capacity of each of the hard disk units 18 is low, thus resulting in 50 percent reduction in storage capacity per 1U. In addition, unless the storage capacity of the 2.5-inch hard disk units 18 increases, it is impossible to complement the decrease in storage capacity by increased number of units alone when the 3.5-inch hard disk units 8 are changed to the 2.5-inch hard disk units 18. It is therefore necessary for the disk array apparatus 2B to implement a structure that allows mounting of additional hard disk units in the apparatus and replacement thereof.
With regard to such a problem, there is no disclosure in Japanese Patent Application Laid-Open Publication Nos. 2003-36669, 2002-343075, 08-137631 and 06-215553, nor is there any description of means for solving the problem.